Variable-diameter wheel-and-tire apparatus for motor vehicles

ABSTRACT

A wheel-and-tire apparatus has a pneumatic tire with two or more circumferential tread sections, the relative diameters of which may be adjusted to select the tread sections in contact with the road. The tire may have one or more air chambers. The apparatus facilitates selective use of tire tread designs and compositions having different performance characteristics to suit particular road conditions and vehicle operating parameters. Adjustment of tread section diameters is accomplished using tread diameter adjustment means having a source of compressed air. Sensors monitor selected operational parameters of the vehicle and transmit corresponding signals to a computer, which selects an optimal configuration of tread section diameters to suit the data from the sensors. The computer sends a corresponding signal instructing the tread diameter adjustment means to adjust the diameter of one or more tread sections as required to achieve the selected configuration of tread section diameters.

[0001] This is a continuation-in-part of U.S. patent application Ser. No. 09/976,268, filed Oct. 15, 2001, the disclosure of which is fully incorporated by reference into the present disclosure.

FIELD OF THE INVENTION

[0002] The present invention relates to pneumatic tires and pneumatic-tired wheel assemblies for motor vehicles, and in particular to such tires and wheel assemblies in which portions of the tire tread are selectively engageable or disengageable with the road surface.

BACKGROUND OF THE INVENTION

[0003] The style and size of tire used on a motor vehicle can affect a number of vehicle operating characteristics, so it is common for vehicle tires to be selected on the basis of particular desired performance characteristics. A high-profile tire may be defined as a tire having a comparatively high aspect ratio, or height-to-width ratio, where the height is the distance measured radially from the tire's circumference to the rim opening. A narrow, high-profile tire with a comparatively smooth tread design may be preferred where fuel economy, low road noise, and ride quality are the main operational concerns. However, high-profile tires do not have ideal handling characteristics in terms of steering, acceleration, and braking, so a wider, low-profile tire, with a coarser tread design and perhaps a softer rubber formulation for improved traction, may be preferred for vehicles intended for high-performance handling under aggressive driving conditions. Unfortunately, low-profile tires do not perform as well as high-profile tires in terms of fuel economy, road noise, ride quality, and tire wear.

[0004] For these reasons, tire selection has traditionally involved compromise, sacrificing certain desirable performance characteristics for others. Vehicles such as family sedans or mini-vans, which are mainly intended for comparatively sedate driving styles and straight-line highway driving, are typically fitted with softer-riding high-profile tires, while sports sedans and sports cars are commonly fitted with low-profile high-performance tires. Each of these compromises works acceptably when the vehicles in question are being operated according to their primary intended functions, but both suffer from significant drawbacks when operational conditions change. A vehicle riding on typical high-profile tires will be more difficult to handle confidently and safely when travelling fast on narrow, winding roads where tight cornering and hard braking may be required, especially when traction is poor due to rough, wet, or icy road surface conditions. In contrast, a vehicle with low-profile, high-performance tires will generally handle much more responsively under such adverse conditions than if it had high-profile tires, but on the freeways it will give a rougher and noisier ride, with poorer fuel economy.

[0005] The prior art discloses numerous attempts to provide vehicle tire systems with variable characteristics to adapt to different operating conditions, including inventions which use multiple-tire assemblies. For example, U.S. Pat. No. 2,751,959, issued to Blomquist on Jun. 26, 1956, discloses a tire-and-wheel assembly having a selectively inflatable auxiliary tire coaxially disposed between two conventional tires, on a specialized telescoping rim and axle assembly. The auxiliary tire has a unique accordion-like construction. The diameter of the auxiliary tire when uninflated is less than that of the two conventional tires, so the auxiliary tire is not in contact with the road surface when in its uninflated state. When inflated, its diameter expands to match that of the conventional tires, and it also expands laterally, displacing the outboard conventional tire further outboard. Accordingly, inflation of the auxiliary tire greatly increases the total width of the wheel assembly and the total area of tire contact with the road surface, thereby providing improved traction. While this invention may be useful in adapting vehicles for use in some adverse conditions, such as soft or swampy terrain, it has numerous drawbacks including the need for a complicated rim and axle assembly to permit expansion of the auxiliary tire and lateral displacement of the outboard tire. As well, the auxiliary tire is of specialized construction and is correspondingly more expensive than a conventional tire.

[0006] In U.S. Pat. No. 5,788,335, issued to O'Brien on Aug. 4, 1998, and in related U.S. Pat. No. 6,022,082, issued to O'Brien on Feb. 8, 2000, a studded, selectively- inflatable auxiliary tire of specialized construction is coaxially disposed between two conventional tires. As in Blomquist, the uninflated diameter of the auxiliary tire in the O'Brien patents is less than that of the conventional tires. Upon inflation, the auxiliary tire expands in diameter (but does not expand laterally as in Blomquist) until it substantially matches the diameter of the conventional tires, such that the studs of the auxiliary tire may engage the road surface. The auxiliary tire thus may be inflated or deflated as desired, to suit particular road conditions. The auxiliary tire of U.S. Pat. No. 5,788,335 is expressly not intended to carry any of the vehicle weight, whereas U.S. Pat. No. 6,022,082 contemplates that all three tires may be load-carrying. However, the two conventional tires carry vehicle loads at all times.

[0007] The inventions disclosed in the O'Brien patents cited above are directed primarily to providing enhanced traction on slippery road surfaces, with the means for providing enhanced traction being disengageable when road conditions are favourable. Other prior art references directed toward the same general objective, in the context of either single-tire or double-tire assemblies, include the following:

[0008] U.S. Pat. No. 2,201,632, issued May 21, 1940 (Roessel)

[0009] U.S. Pat. No. 2,241,849, issued May 13, 1941 (Fuchs)

[0010] U.S. Pat. No. 2,254,318, issued Sep. 2, 1941 (Roessel)

[0011] U.S. Pat. No. 2,765,199, issued Oct. 2, 1956 (Partin)

[0012] U.S. Pat. No. 5,810,451, issued Sep. 22, 1998 (O'Brien)

[0013] U.S. Pat. No. 5,839,795, issued Nov. 24, 1998 (Matsuda et al.)

[0014] U.S. Pat. No. 6,044,883, issued Apr. 4, 2000 (Noyes)

[0015] While the inventions disclosed in these prior art references may be effective in providing increased traction and skid resistance on wet or icy roads, they do not address other desirable objectives such as selectively optimizing ride quality, fuel economy, and general handling characteristics to suit varying road conditions. Furthermore, these inventions typically involve complex traction mechanisms or tires of specialized construction. All of the above-cited prior art inventions embody one or more conventional tires which are in load-bearing contact with the road surface at all times, regardless of whether the inventions' particular traction enhancement means are engaged, and regardless of the road conditions being travelled on.

[0016] For the foregoing reasons, there is a need for a vehicle tire system in which performance parameters including traction, acceleration, braking, cornering, ride quality, and fuel economy may be selectively optimized to suit specific road characteristics and surface conditions. In addition, there is a need for a vehicle tire system in which performance parameters may be automatically optimized to suit road conditions according to selected criteria, without requiring input or selection from the vehicle operator.

[0017] The invention disclosed in the applicant's U.S. patent application Ser. No. 09/976,268 (the “parent application”) addresses the foregoing needs in a multiple-tired wheel assembly which may be mounted on a vehicle in place of a conventional single-tire or dual-tire assembly. The disclosure of the parent application teaches a wheel-and-tire apparatus including an assembly of two or more coaxially-mounted tires, plus means for adjusting the diameter of one or more tires in the assembly, which may be adjusted such that all of the tires, or only one or some of the tires, will be in contact with the road surface over which the vehicle is travelling. The apparatus therefore facilitates the selective use of tires having different performance characteristics, as may be desired or preferred to suit particular road conditions or vehicle operating conditions. Adjustment of the relative diameters of the tires may be accomplished by inflating or partially deflating a particular tire or combination of tires, using one or more pneumatic pumps. Alternatively, tire diameter adjustment may be accomplished by mechanical deformation of one or more tires in the assembly.

[0018] Although tire diameter adjustment may be controlled manually, the invention taught by the parent application also provides for automatic tire diameter adjustment through use of sensors which are mounted in the vehicle and which sense selected operational parameters; e.g., speed, acceleration, steering input, and braking input. The sensors transmit corresponding signals to a computer which, using a program stored in a memory in the computer, selects an optimal tire configuration to suit the particular combination of operational parameters received from the sensors. The computer then transmits a corresponding signal instructing the tire diameter adjustment means, be it pneumatic pump means or mechanical deformation means or other means, to adjust the diameter of one or more tires in the assembly as required to achieve the selected optimal tire configuration.

[0019] The invention disclosed in the parent application thus provides effective means for addressing the aforesaid need for a vehicle tire system in which performance parameters including traction, acceleration, braking, cornering, ride quality, and fuel economy may be selectively optimized to suit specific road characteristics and surface conditions, and a vehicle tire system in which such performance parameters may be automatically optimized to suit road conditions according to selected criteria, without requiring input or selection from the vehicle operator. However, it is also desirable to address these needs in apparatus requiring only one wheel rim with only one tire at each vehicle wheel location. Accordingly, the present invention is directed to providing apparatus to address the foregoing needs using only one wheel rim with only one tire at each vehicle wheel location, and, further, doing so substantially on the basis of fundamental concepts described in the parent application.

BRIEF SUMMARY OF THE INVENTION

[0020] In general terms, the present invention is a wheel-and-tire apparatus including a pneumatic tire mounted on a wheel rim, for mounting on a motor vehicle in place of a conventional single-tire or dual-tire assembly. The pneumatic tire of the invention has two or more circumferential tread sections which may have different tread patterns if desired, or may incorporate different materials having different physical properties. The invention also includes means for selectively varying the diameter of the tread sections such that the number of tread sections in contact with the road surface varies as well. The invention thus facilitates the selective use of tire tread designs and material compositions having different performance characteristics, as may be desired or preferred to suit particular road conditions or vehicle operating conditions.

[0021] Although tread section diameter adjustment may be controlled manually, the present invention also provides for automatic tread diameter adjustment through use of sensors which are mounted in the vehicle and which sense one or more selected operational parameters (e.g., speed, acceleration, steering input, braking input, or other parameters capable of being monitored by sensors known in the art). The sensors transmit corresponding signals to a computer which, using a program stored in a memory in the computer, selects an optimal configuration of tread section diameters to suit the particular combination of operational parameters received from the sensors. The computer then transmits a corresponding signal instructing the tread diameter adjustment means to adjust the diameter of one or more tread sections in the assembly as required to achieve the selected configuration of tread section diameters.

[0022] Accordingly, in one aspect the invention is a wheel-and-tire apparatus for mounting on the wheel hub of a motor vehicle, said apparatus comprising:

[0023] (a) a pneumatic tire having:

[0024] (i) an inboard sidewall and an outboard sidewall, each having a circular outer edge and a circular opening defining an inner edge;

[0025] (ii) a circumferential tread band disposed between and sealingly interconnecting the outer edges of the sidewalls, said tread band having an exterior surface and an interior surface, said exterior surface having two circumferential tread channels dividing the tread band into an inboard tread section, a central tread section, and an outboard tread section; and

[0026] (iii) two spaced internal walls, each being generally aligned with one of the tread channels, and each having:

[0027] (A) a circular outer edge sealingly connected to the interior surface of the tread section; and

[0028] (B) a circular opening defining an inner edge;

[0029] (b) an annular wheel rim defining four annular shoulders corresponding to the inner edges of the sidewalls and internal walls;

[0030] (c) means for pumping compressed air into each air chamber, and for exhausting air therefrom; and

[0031] (d) tread diameter adjustment means, whereby the relative diameters of the tread sections may be selectively varied;

[0032] said pneumatic tire being coaxially mounted on the wheel rim such that the sidewalls, internal walls, and tread sections define an inboard air chamber, a central air chamber, and an outboard air chamber, and such that each said inner edge will be urged into continuous airtight contact with a corresponding shoulder upon inflation of the air chambers.

[0033] In the preferred embodiment, the apparatus may be selectively configured such that the diameter of the central tread section is greater than the diameter of the inboard and outboard tread sections, or such that the diameter of the central tread section is substantially equal to the diameter of the inboard and outboard tread sections.

[0034] In an alternative embodiment, the apparatus may be selectively configured such that the diameter of the central tread section is smaller than the diameter of the inboard and outboard tread sections, or such that the diameter of the central tread section is substantially equal to the diameter of the inboard and outboard tread sections.

[0035] In a further alternative embodiment, the apparatus may be selectively configured such that the diameter of the central tread section is either smaller than, greater than, or substantially equally to the diameter of the inboard and outboard tread sections.

[0036] In any of these embodiments, the various possible configurations of relative tread section diameters may be accomplished by varying the diameter of the central tread section only, by varying the diameter of the inboard and outboard tread sections only, or by varying the diameter of all three tread sections.

[0037] In the preferred embodiment, the tread diameter adjustment means includes at least one pneumatic pump. For example, a single pump may be provided, with an air outlet in fluid communication with the central air chamber, and with the capability of pumping compressed air into, or exhausting air out of, the central air chamber, as may be desired. Alternatively, additional pumps may be provided in association with either or both of the inboard and outboard air chambers.

[0038] In an alternative embodiment, the tread diameter adjustment means includes a compressed air storage tank mounted in a convenient location within the vehicle. Compressed air lines connect the compressed air tank to one or more of the air chambers of the tire, as may be desired, using swivel-type fittings well known in the art for maintaining the connection of the air lines to the air chambers despite rotation of the tire-and-wheel assembly.

[0039] The preferred embodiment also includes sensor and control means for monitoring operational parameters of the motor vehicle, and for activating the tread diameter adjustment means in response to changes in the operational parameters. The sensor and control means comprises:

[0040] (a) an actuator associated with the tread diameter adjustment means;

[0041] (b) one or more sensors, each sensor being capable of measuring a selected operational parameter of the vehicle, and each sensor having a sensor communication link for carrying signals corresponding to operational parameter measurements made by the sensor;

[0042] (c) a computer having a memory, said computer being in communication with each sensor by means of said sensor communication link or links, said computer being for processing operational parameter measurement signals received from the sensor or sensors, and for determining a selected configuration of tread section diameters corresponding to the operational parameter measurements, in accordance with a program stored in the memory; and

[0043] (d) an actuator communication link, for carrying from the computer to the actuator a signal corresponding to the selected configuration of tread section diameters;

[0044] wherein the actuator automatically actuates the tread diameter adjustment means in response to signals received from the computer so as to adjust the apparatus in accordance with the selected configuration of tread section diameters.

[0045] An alternative embodiment is similar to the preferred embodiment described above, except that the tire has only one tread channel and one internal wall, and, accordingly, only inboard and outboard tread sections, and only inboard and outboard air chambers. In this embodiment, the apparatus may be selectively configured such that the diameter of the inboard tread section is either greater than or substantially equally to the diameter of the outboard tread section. Alternatively, the apparatus may be selectively configured such that the diameter of the inboard tread section is smaller than the diameter of the outboard tread section. In a further alternative embodiment, the apparatus may be selectively configured such that the diameter of the inboard tread section is either smaller than, greater than, or substantially equally to the diameter of the outboard tread section.

[0046] In any of these embodiments, the various possible configurations of the apparatus may be accomplished by varying the diameter of the inboard tread section only, by varying the diameter of the outboard tread section only, or by varying the diameter of both the inboard outboard tread sections. Operation of the tread diameter adjustment means may be effected in essentially the same way as described previously herein for the preferred embodiment, with modifications as obviously required to suit the two-tread-section embodiment of the apparatus.

[0047] In a further alternative embodiment, the invention is a wheel-and-tire apparatus for mounting on the wheel hub of a motor vehicle, said apparatus comprising:

[0048] (a) a wheel rim;

[0049] (b) a pneumatic tire having two sidewalls plus a circumferential tread band disposed between and sealingly interconnecting the outer edges of the sidewalls, said pneumatic tire being sealingly and coaxially mounted on the wheel rim so as to form an air chamber;

[0050] (c) inflation means, for pumping compressed air into the air chamber or exhausting air therefrom; and

[0051] (d) sensor and control means for monitoring operational parameters of the motor vehicle, and for activating the inflation means in response to changes in the operational parameters.

[0052] The inflation means may include one or more pneumatic pumps. Alternatively, the inflation means may include a compressed air storage tank, with associated compressed air lines connected to the air chamber.

[0053] In another aspect, the invention is a pneumatic tire, for mounting on a motor vehicle wheel rim, said pneumatic tire having:

[0054] (a) an inboard sidewall and an outboard sidewall, each having a circular outer edge and a circular opening defining an inner edge;

[0055] (b) a circumferential tread band disposed between and sealingly interconnecting the outer edges of the sidewalls, said tread band having an exterior surface and an interior surface, said exterior surface having two circumferential tread channels dividing the tread band into an inboard tread section, a central tread section, and an outboard tread section; and

[0056] (c) two spaced internal walls, each being generally aligned with one of the tread channels, and each having:

[0057] (i) a circular outer edge sealingly connected to the interior surface of the tread section; and

[0058] (ii) a circular opening defining an inner edge;

[0059] such that the sidewalls, internal walls, and tread sections define an inboard air chamber, a central air chamber, and an outboard air chamber.

[0060] In an alternative embodiment, the pneumatic tire of the invention has only one tread channel and one internal wall, and, accordingly, only inboard and outboard tread sections, and only inboard and outboard air chambers.

BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Embodiments of the invention will now be described with reference to the accompanying figures, in which numerical references denote like parts, and in which:

[0062]FIG. 1 is a schematic drawing of the preferred embodiment of the invention, conceptually illustrating the sensor and control means of the invention.

[0063]FIG. 2A is a cross-section of the preferred embodiment, in a first configuration.

[0064]FIG. 2B is a cross-section of the preferred embodiment, in a second configuration.

[0065]FIG. 3A is a cross-section of an alternative embodiment, in a first configuration.

[0066]FIG. 3B is a cross-section of an alternative embodiment, in a second configuration.

[0067]FIGS. 4A and 4B are partial cross-sectional views of a further alternative embodiment, illustrated in various configurations.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0068] In the preferred embodiment as illustrated in FIGS. 1, 2A, and 2B, the wheel-and-tire apparatus of the present invention, generally indicated by reference numeral 100, includes a pneumatic tire 110 mountable on a wheel rim 130 with four annular shoulders 132. Tire 110 includes an inboard sidewall 112, two spaced internal walls 114, and an outboard sidewall 116, plus a circumferential tread band 118. The inboard sidewall 112 has a circumferential outer edge and a central circular opening which defines a circular inner edge. Similarly, each internal wall 114 has a circumferential outer edge and a central circular opening which defines a circular inner edge, and the outboard sidewall 116 has a circumferential outer edge and a central circular opening which defines a circular inner edge.

[0069] The tread band 118 extends between outer edges of the inboard sidewall 112 and the outboard sidewall 116, and is connected thereto in sealed airtight fashion. Formed into the tread band 118 are two circumferential tread channels 120 which subdivide the exterior surface of the tread band into an inboard tread section 122, a central tread section 124, and an outboard tread section 126. The outer edge of each internal wall 114 is connected to the tread band 118 in sealed airtight fashion, in general alignment with one of the tread channels 120.

[0070] Although the foregoing description refers to the sidewalls 112 and 116 and internal walls 114 as discrete elements connected to the tread band 118, it will be readily apparent to those skilled in the art that one or more of the sidewalls 112 and 116 and internal walls 114 could be manufactured integrally with the tread band 118 in accordance with methods well known in the tire-manufacturing industry.

[0071] When the tire 110 is mounted on the rim 130, the inner edges of the inboard sidewall 112, interior walls 114, and the outboard sidewall 116 respectively will be seated against corresponding annular shoulders 132 of rim 130 so as to form an inboard air chamber 142, a central air chamber 144, and an outboard air chamber 146. The wheel-and-tire apparatus 110 is coaxially mounted onto a wheel hub H of a motor vehicle 60, in place of a conventional single-tire or dual-tire assembly, and is coaxially rotatable about axis A of the wheel hub H.

[0072] Tread diameter adjustment means, conceptually illustrated in FIGS. 2A and 2B and indicated by reference numeral 150, is provided in association with the central air chamber 144, for increasing or decreasing the diameter of the central air chamber 144 as may be desired. In the preferred embodiment, the tread diameter adjustment means 150 will include a pneumatic pump mounted in association with the rim 130, with a compressed air outlet in fluid communication with the interior space inside the central air chamber 144. With the use of appropriate valving well known in the field of the invention, the pump will be capable of pumping compressed air into the central air chamber 144, thereby increasing the outer diameter of central tread section 124, or exhausting air from inside the central air chamber 144, thus decreasing the outer diameter of central tread section 124.

[0073] In the preferred embodiment, the pneumatic pump will be a self-contained air compressor which can be mounted to the rim 130 and which harnesses energy from rotation of the rim 130 to provide the power needed to operate the compressor. One example of a self-contained air compressor having capabilities of this nature is the SMART PUMP (TM) manufactured by the Cycloid Company of Pittsburgh, Pa. However, the pneumatic pump of the tread diameter adjustment means 150 can be any pneumatic pump which is capable of inflating or deflating a rotating tire.

[0074] In an alternative embodiment, the tread diameter adjustment means 150 includes a compressed air storage tank (not shown) mounted in a convenient location within the vehicle 60. Compressed air lines connect the compressed air tank to one or more of the air chambers of the tire, as may be desired, using swivel-type fittings well known in the art for maintaining the connection of the air lines to the air chambers despite rotation of the tire-and-wheel assembly. Control valves in the air lines may be used to control the flow of compressed air, as needed, from the compressed air tank to the air chambers. The compressed air tank may be charged, either continuously or intermittently, by an air compressor mounted in the vehicle 60. Alternatively, the compressed air tank may be intermittently charged or re-charged from a stationary compressor, as required according to use of the vehicle 60.

[0075] It will be readily apparent that, whatever type of the tread diameter adjustment means 150 is used, when the tread diameter adjustment means 150 is activated to increase the outer diameter of central tread section 124 to a dimension sufficiently greater than the outer diameters of the inboard tread section 122 and the outboard tread section 126, only the central tread section 124 will be in contact with a road surface 40 which the vehicle is travelling upon, as illustrated in FIG. 2A. When the outer diameter of the central tread section 124 is adjusted to a dimension substantially equal to the outer diameters of the inboard tread section 122 and the outboard tread section 126, the inboard tread section 122, the central tread section 124, and the outboard tread section 126 will all be in contact with the road surface 40, as illustrated in FIG. 2B. Although not illustrated in the Figures, it may be clearly seen that if the outer diameter of the central tread section 124 is decreased to a dimension sufficiently smaller than the outer diameters of the inboard tread section 122 and the outboard tread section 126, only the inboard tread section 122 and the outboard tread section 126 will be in contact with the road surface 40. It will also be readily seen that variances in the relative outer diameters of the inboard tread section 122, the central tread section 124, and the outboard tread section 126, as described above, may be achieved equally effectively using different variants of the tread diameter adjustment means 150, without departing from the essential concept of the invention. For example, the tread diameter adjustment means 150 could include a pneumatic pump or pumps which increase or decrease the outer diameters of the inboard tread section 122 and the outboard tread section 126, while the central tread section 124 undergoes no change. Alternatively, the tread diameter adjustment means 150 could include two or more pneumatic or pumps which can be operated independently or in combination to increase or decrease the outer diameter of all three tires to achieve a desired configuration.

[0076] Although the tire 110 of the preferred embodiment features two internal walls 114 and therefore three air chambers, the essential concept of the invention may be applied in a tire have few than three air chambers. For example, as illustrated in FIGS. 3A and 3B, an alternative embodiment of the wheel-and-tire apparatus of the present invention, generally indicated by reference numeral 101, has a pneumatic tire 111 mountable on a wheel rim 131 with three annular shoulders 132. Tire 111 has only one internal wall 114 and only one tread channel 120, and therefore no central air chamber and no central tread section; all other components are substantially the same as those of tire 110 described previously and are referenced herein with the same reference numbers. In FIGS. 3A and 3B, the tread diameter adjustment means 150 is illustrated in association with the inboard air chamber 142, for increasing or decreasing the diameter of the inboard tread section 122 as may be desired. However, the tread diameter adjustment means 150 could also be provided in association with the outboard air chamber 146, or both the inboard air chamber 142 and the outboard air chamber 146.

[0077] When the tread diameter adjustment means 150 is activated to increase the outer diameter of the inboard tread section 122 to a dimension sufficiently greater than the outer diameter of the outboard tread section 126, only the inboard tread section 122 will be in contact with the road surface 40, as illustrated in FIG. 3A. When the outer diameter of the inboard tread section 122 is adjusted to a dimension substantially equal to the outer diameter of the outboard tread section 126, both the inboard tread section 122 and the outboard tread section 126 will be in contact with the road surface 40, as illustrated in FIG. 3B. Although not illustrated in the Figures, it may be clearly seen that if the outer diameter of the inboard tread section 122 is decreased to a dimension sufficiently smaller than the outer diameter of the outboard tread section 126, only the outboard tread section 126 will be in contact with the road surface 40.

[0078] It will be readily seen that variances in the relative outer diameters of the inboard tread section 122 and the outboard tread section 126, in the alternative embodiment described above, may be achieved equally effectively using different variants of the tread diameter adjustment means 150, without departing from the essential concept of the invention. For example, the tread diameter adjustment means 150 may include a pneumatic pump mounted in association with the outboard air chamber 146 which can increase or decrease the outer diameter of the outboard tread section 126, while the inboard tread section 122 undergoes no change. Alternatively, the tread diameter adjustment means 150 may include two pneumatic pumps which can be operated independently or in combination to increase or decrease the outer diameter of the inboard tread section 122 and the outboard tread section 126 to achieve a desired configuration.

[0079] In the preferred embodiment, as illustrated in FIG. 1, the invention features sensor and control means 50 which includes one or more sensors 52 mounted in selected locations in the vehicle 60, plus an actuator (not shown) associated with the tread diameter adjustment means 150. In this embodiment, the tread diameter adjustment means 150 may operate automatically, without direct input from the vehicle operator. Each sensor 52 monitors a selected operational parameter for the vehicle 60, such as vehicle speed, acceleration, engine speed, selected transmission gear, tire pressure, tire temperature, steering load, shock absorber load, or braking load. Sensors capable of monitoring these and numerous other parameters are readily available, being commonly used in the telemetry systems for high performance race cars. The sensor and control means 50 also includes a computer 54 with a memory 56, mounted in a convenient location in the vehicle 60. Each sensor 52 is in communication with the computer 54 by means of a sensor communication link, which may be either hard-wired or wireless, as conceptually indicated by reference numeral 53. Each sensor transmits a signal to the computer 54 corresponding to the status of the operational parameter being monitored by the sensor 52. The computer 54, using a program stored in memory 56, processes the data corresponding to the signals received from all of the sensors 52 to determine an optimal configuration of outer diameters of the tires in the wheel-and-tire assembly 100, to suit the operational parameters of the vehicle at the time of processing by the computer 54. By means of an actuator communication link, which may be either hard-wired or wireless, as conceptually indicated by reference numeral 57, the computer 54 then transmits a control signal to the actuator (not shown), which actuates the tread diameter adjustment means 150 as appropriate to achieve the desired configuration of tread diameters.

[0080] It will be readily seen that the present invention provides for considerable flexibility with respect to the characteristics of the tire tread or treads which will be in contact with the road at any particular time, according to the preferences of the vehicle operator. For example, in the preferred embodiment, the central tire section formed by the internal walls 114 and central tread section 144 might be made in the general fashion of a conventional narrow, soft-riding, high-profile tire, while the inboard tread section 122 and the outboard tread section 126 have tread designs, and perhaps material compositions, of types commonly used for high-performance, low-profile tires. Using this configuration, the program stored in the memory 56 might provide for differential tread diameter adjustment such that only the central tread section 144 will be in contact with the road surface 40 during essentially straight-line driving on main highways, but also such that the more high-performance inboard tread section 142 and outboard tread section 146 will be automatically deployed into contact with the road surface 40 in a variety of different operating conditions, such as under brisk acceleration, hard steering, or heavy braking. It will be readily apparent to those skilled in the art that the program stored in memory 56 may be custom-designed using well-known programming techniques to accommodate various possible protocols for operation of the tread diameter adjustment means 150, according to selected operational parameters.

[0081] The wheel-and-tire apparatus of the present invention may be fitted at each wheel location of a particular vehicle, or at selected wheel locations only, as may be desired. For example, the apparatus could be used at rear wheel locations only, while using conventional single-tire assemblies at front wheel locations. Alternatively, the apparatus could be used at front wheel locations only, while using conventional single-tire assemblies at rear wheel locations. A separate computer 54 may be provided to control the apparatus at each wheel location. Alternatively, however, a single computer 54 may be used to control the apparatus at more than one location, without departing from the essential concept of the invention.

[0082] In an alternative embodiment of the invention, the tread diameter adjustment means 150 may be controlled manually by the operator of the vehicle. Accordingly, the apparatus of the invention may include a control switch (not shown), mounted for convenient access by the operator, whereby the operator may select from among two or more configurations of tread diameters, whereupon the control switch transmits a corresponding signal to the tread diameter adjustment means 150, which in turn adjusts the relative outer diameters of the inboard tread section 122, the central tread section 124, and the outboard tread section 126 as appropriate to achieve the selected configuration.

[0083] In accordance with the present invention, a vehicle operator can selectively deploy one or more types of tire tread at a given wheel location, thereby obtaining an optimized combination of the practical and economic benefits available from each type of tire tread used. For example, when the central section of the pneumatic tire is designed and fabricated in the general fashion of conventional high-profile tires, and the inboard and outboard tread sections are made in the fashion of treads on wide, low-profile tires, the invention allows the central tread section to be deployed when a soft, comfortable ride and optimal fuel economy are desired. In this configuration, the low-profile inboard and outboard tread sections will rotate without any contact with the road, and therefore will not be subject to wear. As may be warranted by changing operational conditions, the low-profile inboard and outboard tread sections can be deployed instead of or in addition to the central tread section to provide improved and safer vehicle handling. Although a combination of high-profile and low-profile tread designs is referred to in the foregoing example for illustrative purposes, the present invention is adaptable for use with a variety of different tread designs.

[0084] In a further alternative embodiment, illustrated in FIGS. 4A and 4B and generally indicated by reference numeral 102, the objectives of the invention may be met using a tire 160 having a single air chamber 162 with no internal walls. The tire 160 is of conventional cross-section and is mounted on a conventional rim 170. The tire has a tread band 164. The tire 160 may be inflated or deflated by means of inflation means, depicted conceptually and indicated by reference numeral 180. The inflation means 180 may comprise one or more pneumatic pumps mounted in association with the rim 170. Alternatively, the inflation means 180 may comprise a compressed air storage tank having suitable compressed air lines connecting to the air chamber of the tire 160. The operation of the inflation means 180 is controlled by sensor and control means 50 in much the same fashion as previously described in the context of other embodiments of the invention, adjusting the air pressure in the tire 160, and therefore the diameter and tread curvature of the tire 160, in accordance with a program stored in the computer 54 of the sensor and control means 50, depending on operational parameter readings taken by the sensors 52.

[0085] As clearly shown in FIGS. 4A and 4B, the portion of the tread band 164 in contact with the road will vary depending on the inflation of the tire 160. When the tire 160 is highly inflated, only a central portion of the tread band 164 is in contact with the road, as seen in FIG. 4A. As the inflation of the tire 160 is reduced, contact between the tread band 164 and the road increases, up to the point where the full width of the tread band 164 is in contact with the road, as shown in FIG. 4B.

[0086] In accordance with this embodiment of the invention, therefore, the inflation means 180, in conjunction with the sensor and control means 50, may be used to adjust the cross-section of the tire 160 to deploy an optimal portion of tread band 164 into contact with the road, based on measured operational parameters and desired vehicle performance characteristics such as ride quality, handling, tire wear, and fuel economy. For example, it may be desired to have the tire 160 run on only a central portion of the tread band 164 (as shown in FIG. 4A) during straight-line highway driving, while also engaging the outer portions of the tread band 164 (as shown in FIG. 4B) when greater traction is desirable, such as when accelerating or cornering, or when driving on rough surfaces. As well, the tread design and even the materials used for the tread band 164 may be varied across the width of the tread band 164, thereby enhancing the benefits obtainable from this embodiment of the invention.

[0087] It will be readily seen by those skilled in the art that various modifications of the present invention may be devised without departing from the essential concept of the invention, and all such modifications are intended to be included in the scope of the claims appended hereto. 

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:
 1. A wheel-and-tire apparatus for mounting on the wheel hub of a motor vehicle, said apparatus comprising: (a) a pneumatic tire having: (i) an inboard sidewall and an outboard sidewall, each having a circular outer edge and a circular opening defining an inner edge; (ii) a circumferential tread band disposed between and sealingly interconnecting the outer edges of the sidewalls, said tread band having an exterior surface and an interior surface, said exterior surface having two circumferential tread channels dividing the tread band into an inboard tread section, a central tread section, and an outboard tread section; and (iii) two spaced internal walls, each being generally aligned with one of the tread channels, and each having: (A) a circular outer edge sealingly connected to the interior surface of the tread section; and (B) a circular opening defining an inner edge; (b) an annular wheel rim defining four annular shoulders corresponding to the inner edges of the sidewalls and internal walls; (c) means for pumping compressed air into each air chamber, and for exhausting air therefrom; and (d) tread diameter adjustment means, whereby the relative diameters of the tread sections may be selectively varied; said pneumatic tire being coaxially mounted on the wheel rim such that the sidewalls, internal walls, and tread sections define an inboard air chamber, a central air chamber, and an outboard air chamber, and such that each said inner edge will be urged into continuous airtight contact with a corresponding shoulder upon inflation of the air chambers.
 2. The apparatus of claim 1, wherein the relative diameters of the tread sections may be selectively configured such that the diameter of the central tread section is greater than the diameter of the inboard and outboard tread sections, or such that the diameter of the central tread section is substantially equal to the diameter of the inboard and outboard tread sections.
 3. The apparatus of claim 1, wherein the relative diameters of the tread sections may be selectively configured such that the diameter of the central tread section is smaller than the diameter of the inboard and outboard tread sections, or such that the diameter of the central tread section is substantially equal to the diameter of the inboard and outboard tread sections.
 4. The apparatus of claim 1, further comprising sensor and control means for monitoring operational parameters of the motor vehicle, and for activating the tread diameter adjustment means in response to changes in the operational parameters.
 5. The apparatus of claim 4, wherein the sensor and control means comprises: (a) an actuator associated with the tread diameter adjustment means; (b) one or more sensors, each sensor being capable of measuring a selected operational parameter of the vehicle, and each sensor having a sensor communication link for carrying signals corresponding to operational parameter measurements made by the sensor; (c) a computer having a memory, said computer being in communication with each sensor by means of said sensor communication link or links, said computer being for processing operational parameter measurement signals received from the sensor or sensors, and for determining a selected configuration of tread section diameters corresponding to the operational parameter measurements, in accordance with a program stored in the memory; and (d) an actuator communication link, for carrying from the computer to the actuator a signal corresponding to the selected configuration of tread section diameters; wherein the actuator automatically actuates the tread diameter adjustment means in response to signals received from the computer so as to adjust the relative diameters of the tread sections in accordance with the selected configuration of tread section diameters.
 6. The apparatus of claim 1, wherein the tread diameter adjustment means includes a pneumatic pump associated with the central air chamber, said pump having the facility to pump compressed air into the central air chamber or to exhaust air out of the central air chamber, as may be desired.
 7. The apparatus of claim 6, wherein power to operate the pneumatic pump is generated by rotation of the pump with the wheel-and-tire apparatus.
 8. The apparatus of claim 6, wherein the pneumatic pump is battery-powered.
 9. The apparatus of claim 1, further comprising control means whereby the tread diameter adjustment means may be manually activated from within the motor vehicle.
 10. The apparatus of claim 1, wherein the tread diameter adjustment means comprises a compressed air storage tank mounted in the vehicle, with a conduit for delivery of compressed air from the storage tank to the central air chamber.
 11. A wheel-and-tire apparatus for mounting on the wheel hub of a motor vehicle, said apparatus comprising: (a) a pneumatic tire having: (i) an inboard sidewall and an outboard sidewall, each having a circular outer edge and a circular opening defining an inner edge; (ii) a circumferential tread band disposed between and sealingly interconnecting the outer edges of the sidewalls, said tread band having an exterior surface and an interior surface, said exterior surface having a circumferential tread channel dividing the tread band into an inboard tread section and an outboard tread section; and (iii) an internal wall generally aligned with the tread channel, and having: (A) a circular outer edge sealingly connected to the interior surface of the tread section along a line in substantially the same plane as the tread channel; and (B) a circular opening defining an inner edge; (b) an annular wheel rim defining three annular shoulders corresponding to the inner edges of the sidewalls and the internal wall; (c) means for pumping compressed air into each air chamber, and for exhausting air therefrom; and (d) tread diameter adjustment means, whereby the relative diameters of the tread sections may be selectively varied; said pneumatic tire being coaxially mounted on the wheel rim such that the sidewalls, internal walls, and tread sections define an inboard air chamber and an outboard air chamber, and such that each said inner edge will be urged into continuous airtight contact with a corresponding shoulder upon inflation of the air chambers. said pneumatic tire being mounted on said wheel rim so as to be coaxially rotatable.
 12. The apparatus of claim 11, wherein the relative diameters of the tread sections may be selectively configured such that the diameter of the inboard tread section is greater than the diameter of the outboard tread section, or such that the diameter of the inboard tread section is substantially equal to the diameter of the outboard tread section.
 13. The apparatus of claim 11, wherein the relative diameters of the tread sections may be selectively configured such that the diameter of the inboard tread section is smaller than the diameter of the outboard tread section, or such that the diameter of the inboard tread section is substantially equal to the diameter of the outboard tread section.
 14. The apparatus of claim 11, further comprising sensor and control means for monitoring operational parameters of the motor vehicle, and for activating the tread diameter adjustment means in response to changes in the operational parameters.
 15. The apparatus of claim 14, wherein the sensor and control means comprises: (a) an actuator associated with the tread diameter adjustment means; (b) one or more sensors, each sensor being capable of measuring a selected operational parameter of the vehicle, and each sensor having a sensor communication link for carrying signals corresponding to operational parameter measurements made by the sensor; (c) a computer having a memory, said computer being in communication with each sensor by means of said sensor communication link or links, said computer being for processing operational parameter measurement signals received from the sensor or sensors, and for determining a selected configuration of tread section diameters corresponding to the operational parameter measurements, in accordance with a program stored in the memory; and (d) an actuator communication link, for carrying from the computer to the actuator a signal corresponding to the selected configuration of tread section diameters; wherein the actuator automatically actuates the tread diameter adjustment means in response to signals received from the computer so as to adjust the relative diameters of the tread sections in accordance with the selected configuration of tread section diameters.
 16. The apparatus of claim 11, wherein the tread diameter adjustment means includes a pneumatic pump associated with the inboard air chamber, said pump having the facility to pump compressed air into the inboard air chamber or to exhaust air out of the inboard air chamber, as may be desired.
 17. The apparatus of claim 16, wherein power to operate the pneumatic pump is generated by rotation of the pump with the wheel-and-tire apparatus.
 18. The apparatus of claim 16, wherein the pneumatic pump is battery-powered.
 19. The apparatus of claim 11, further comprising control means whereby the tread diameter adjustment means may be manually activated from within the motor vehicle.
 20. The apparatus of claim 11, wherein the tread diameter adjustment means comprises a compressed air storage tank mounted in the vehicle, with a conduit for delivery of compressed air from the storage tank to the central air chamber.
 21. A pneumatic tire, for mounting on a motor vehicle wheel rim, said pneumatic tire having: (a) an inboard sidewall and an outboard sidewall, each having a circular outer edge and a circular opening defining an inner edge; (b) a circumferential tread band disposed between and sealingly interconnecting the outer edges of the sidewalls, said tread band having an exterior surface and an interior surface, said exterior surface having two circumferential tread channels dividing the tread band into an inboard tread section, a central tread section, and an outboard tread section; and (c) two spaced internal walls, each being generally aligned with one of the tread channels, and each having: (i) a circular outer edge sealingly connected to the interior surface of the tread section; and (ii) a circular opening defining an inner edge; such that the sidewalls, internal walls, and tread sections define an inboard air chamber, a central air chamber, and an outboard air chamber.
 22. A pneumatic tire, for mounting on a motor vehicle wheel rim, said pneumatic tire having: (a) an inboard sidewall and an outboard sidewall, each having a circular outer edge and a circular opening defining an inner edge; (b) a circumferential tread band disposed between and sealingly interconnecting the outer edges of the sidewalls, said tread band having an exterior surface and an interior surface, said exterior surface having a circumferential tread channel dividing the tread band into an inboard tread section and an outboard tread section; and (c) an internal wall having: (i) a circular outer edge sealingly connected to the interior surface of the tread section along a line in substantially the same plane as the tread channel; and (ii) a circular opening defining an inner edge; such that the sidewalls, internal wall, and tread sections define an inboard air chamber and an outboard air chamber.
 23. A wheel-and-tire apparatus for mounting on the wheel hub of a motor vehicle, said apparatus comprising: (a) a wheel rim; (b) a pneumatic tire having two sidewalls plus a circumferential tread band disposed between and sealingly interconnecting the outer edges of the sidewalls, said pneumatic tire being sealingly and coaxially mounted on the wheel rim so as to form an air chamber; (c) inflation means, for pumping compressed air into the air chamber or exhausting air therefrom; and (d) sensor and control means for monitoring operational parameters of the motor vehicle, and for activating the inflation means in response to changes in the operational parameters.
 24. The apparatus of claim 23, wherein the sensor and control means comprises: (a) an actuator associated with the inflation means; (b) one or more sensors, each sensor being capable of measuring a selected operational parameter of the vehicle, and each sensor having a sensor communication link for carrying signals corresponding to operational parameter measurements made by the sensor; (c) a computer having a memory, said computer being in communication with each sensor by means of said sensor communication link or links, said computer being for processing operational parameter measurement signals received from the sensor or sensors, and for determining a selected degree of tire inflation corresponding to the operational parameter measurements, in accordance with a program stored in the memory; and (d) an actuator communication link, for carrying from the computer to the actuator a signal corresponding to the selected degree of tire inflation; wherein the actuator automatically actuates the inflation means in response to signals received from the computer so as to inflate or deflate the tire in accordance with the selected degree of tire inflation.
 25. The apparatus of claim 23, wherein the inflation means includes a pneumatic pump.
 26. The apparatus of claim 25, wherein power to operate the pneumatic pump is generated by rotation of the pump with the wheel-and-tire apparatus.
 27. The apparatus of claim 25, wherein the pneumatic pump is battery-powered.
 28. The apparatus of claim 23, wherein the tread diameter adjustment means comprises a compressed air storage tank mounted in the vehicle, with a conduit for delivery of compressed air from the storage tank to the central air chamber.
 29. The apparatus of claim 23, further comprising control means whereby the inflation means may be manually activated from within the motor vehicle. 